1. Field of the Invention
The invention relates to a housing arrangement for accommodating electronic assemblies, in particular a flat desktop PC or multimedia housing, comprising a bottom plate, front and rear sides, as well as a hood-type, removable cover, a fan driven by an electric motor, and chambers or sections formed in the housing, according to the preamble of claim 1.
2. Discussion of the Background
From the German Utility Model G 91 08 160.2 an outer housing for a magnetooptical mass storage is known which comprises a fan which introduces a directed air stream into the housing via a suitable filter in such a manner that said air stream can be directed through the drive of the storage. With such a housing, the current supply is arranged at a lateral distance from the housing and is also cooled by means of a partial air stream. The use of a filter is necessary because contamination of the write/read unit of a magnetooptical storage can result in the failure of same.
A so-called compact industrial computer is disclosed in Utility Model G 90 05 147.5. Therein, the possibility of cooling components which are located within the computer is also provided for. To be concrete, shorter plug-in boards and a fan installed in the front are to be utilised so that the installation depth is reduced compared to that which has previously been known. With a switchgear cabinet installation, the air is to be drawn in in the front area and discharged in the rear area of the housing. With a stand-alone installation in a contaminated environment the housing according to G 90 05 147.5 is sealed, and filters are employed. The provided fans blow in opposite directions so that an air circulation under utilisation of air baffles can be achieved within the computer. In an embodiment the filter mats are replaced by a heat exchanger so that a distinction is to be made between an internal air circulation circuit and an external heat dissipation.
In addition, a cooling unit with optimised cooling air control within a data processing system is known from IBM Technical Disclosure Bulletin, Vol. 25, No. 7B, December 1982. The fan provided therein is arranged near a CPU heat sink connected with same, with the air stream via intake openings in the housing being first utilised for a switching power supply unit and only then for cooling of the CPU. The air discharge opening is located on the housing top.
The above described housing arrangements with integrated ventilation, however, have a not optimised cooling air flow in common, in particular under the aspect of an undesired noise generation. With housing arrangements which accommodate electronic devices, e.g. multimedia means and which are also employed in home applications, it is generally required to keep the noise emission of the device itself, which the user conceives as annoying, at a low level.
From the above it is therefore the object of the invention to specify a further developed housing arrangement for the accommodation of electronic assemblies, in particular a flat desktop PC or multimedia housing, which achieves an optimised cooling of the components located in its interior with a simultaneous minimum noise emission so that, on the one hand, legal requirements for the application of such devices at the workplace are met and, on the other hand, the use of such a device in the private area is not experienced as annoying.
The solution of the object of the invention is by means of a subject matter according to the characteristics of claim 1, with the dependent claims comprising at least suitable embodiments and further developments.
According to the invention, a fresh air duct is provided in the interior of the housing, which extends essentially parallel to the base plate and spaced apart from same at a predetermined height, with the fresh air duct, apart from lateral air intake openings, being sealed at the suction side against the remaining housing and the chambers or sections which are located in the interior of the housing.
At the far end of the air intake opening of the fresh air duct a recess is provided for the accommodation of a fan, with the fan being designed in such a manner that it blows vertically into the chamber located below the fresh air duct.
The lower chamber is communicating with a lateral exhaust air duct, via which the heated exhaust air is positively directed to be laterally discharged from the housing.
In the flow direction below the fan, at least one electronic assembly and heat source is located, in particular a CPU with heat sink, against which the fan blows. Upstream of the recess for accommodating the fan, a further recess is provided in the fresh air duct which serves for mounting an assembly to be cooled. This assembly extends into the lower chamber. The latter assembly can, in particular, be a hard disk drive, with the surface portion to be cooled being encompassed by the further recess. At the same time, there is the possibility to mount this hard disk in a sound-dampened manner by means of an elastic support in the further recess.
The fresh air duct can be manufactured from a sheet metal moulded part or an injection moulded part, with the hood-type cover possessing lateral air intake openings and sealing the fresh air duct from above.
In the lateral exhaust duct a current supply assembly, in particular a switching power supply unit is arranged in open frame construction. The exhaust duct is formed by a partition wall in the housing interior and the hood-type cover, with the cover comprising lateral openings for the air discharge.
The cover is, in particular, essentially of a U shape, with the air intake openings being formed in one leg and the air discharge openings being formed in the opposite second leg. These openings can be realised e.g. by punching or drilling.
Further assemblies to be cooled are arranged at the partition wall in the interior of the housing, being in thermal contact with same.
Due to the arrangement of an electronic assembly, in particular of a CPU with a passive heat sink below the fan, said heat sink is immediately blown against with an additional desired turbulence of the air stream being effected.
Apart from the sound-dampened support and mounting of the hard disk in the further recess, the fan may as well be secured in the first mentioned recess in a structure-borne insulated manner.
The fan builds up an overpressure within the lower chamber, with the partition wall in the interior of the housing comprising air through holes in a rear area. The partition wall is designed in the form of a double bevel, whereby a further chamber for accommodating the mentioned, in particular, open frame switching power supply unit is formed.
The longer side of the partition wall extends parallel and at a distance from the second leg of the cover, at least until the air discharge openings seen therein.
The at least one electronic assembly arranged in the lower chamber can be accessible from the front side of the housing via a flap, a sliding part, or similar means.
With the presented housing a special cooling air flow is obtained which originates from a lateral air intake with at first a horizontal course within the fresh air duct, with a reversal of direction vertically downward into the lower chamber, with an overpressure build-up and turbulence taking place thereafter. A further reversal of direction takes place horizontally into the lateral exhaust duct, with a pressure relief being effected via the lateral air discharge and the housing openings provided there which are opposite those for the air intake.
The housing concept is further characterised by a split level flat construction, with sources of considerable heat generation being located in a lower plane, sources of medium to low heat generation being located in a mid plane, and a fresh air duct with forced flow being located in an upper plane, with this forced flow extending from top to bottom and exiting laterally.
In the area of the air discharge adjacent to the lower plane, an exhaust duct is located which with respect to height covers all planes, in which at least one further, however, thermally non-critical heat source can be arranged.
According to the invention a directed suction of the cooling air is effected via a special fresh air duct, the suction side of which is sealed against the housing. This air duct simultaneously serves as an upper mounting of, in particular, a hard disk drive and has an opening or recess sealed against the hard disk housing in the area of the hard disk, via which the hard disk at its upper part is continuously subjected to the drawn in air and cooled.
The only fan used in the housing is supported and secured in a horizontal position at the end of the air duct in, for example, rubber or a similar elastic material and blows vertically downward directly against the passive heat sink of the CPU or the processor, respectively, which is located below. As mentioned, this results in an additional turbulence of the air flow which contributes to the cooling of the remaining electronic components.
Due to the sealing of the air duct against the housing, an overpressure is simultaneously generated within the housing, which by correspondingly generously dimensioned openings in the partition wall sealed against the housing, which simultaneously represents the exhaust duct, causes a directed air stream over the heat sink of the switching power supply unit and ensures its cooling. The recess for accommodating the mass storage is slightly larger dimensioned than the disk itself and preferably lined with cellular rubber. The hard disk is supported in this cellular rubber and in turn strongly urged against same by means of the suction duct via cellular rubber strips so that with this embodiment a stable immobile support is given and a structure-born sound transmission substantially avoided.
With the use of hard disk storage devices of very high speeds, this embodiment, in particular, succeeds on the one hand to dissipate the relatively high heat losses and, on the other hand, to reduce the generated noise.